According to a first aspect, the invention more specifically relates to a liquid-dissolved gas characterization facility, this facility including at least a circuit of fluid including first and second branches, the first branch exhibiting a first end for the intake of the liquid and a second end being connected to the second branch, and each branch including at least a valve.
A facility of this type is for example known from Japanese patent application JP 59 026031.
It is known to store fuel gas to ensure the optimal supply thereof to consumers, including at the time of peaks of consumption or upon a potential failure of a supplier.
To this end, it is also known to store gas in a water table. In this configuration, the gas from deposits and conveyed by the transport network, is injected into a porous rock which contains water. A small part of this natural gas is then dissolved in the water of the aquifer.
During follow-up of the activity of these storages, it is necessary to collect quantitative information on the dissolved gas content in the water of the storage water table.
To this end, water samples are collected at the storage pressure (up to 80 bars at well bottom) and are preserved in titanium capsules.
These capsules are then brought to a laboratory where the dissolved gas is extracted and analyzed.
To optimize this characterization operation, it is advisable to extract all the dissolved gases, to determine their volume, and analyze them.
It is known to proceed with this operation by means of equipment using a mercury pump. The principle is to vacuum the capsule containing the liquid sample, and to flow gas by a mercury stream. The dissolved gas is then recovered in a test-tube to determine the volume thereof, then transferred to an analyzer.
However, these manipulations are very long and constraining, notably, because of the toxicity of mercury used and the complexity of the equipment.
Many techniques were proposed for the characterization of gas dissolved in liquids, in particular, in oil or in sea water.
Examples of these techniques are given in patent documents U.S. Pat. No. 6,602,327, U.S. Pat. No. 4,853,006, US2060242, US20030084916, U.S. Pat. No. 5,645,625, and U.S. Pat. No. 5,183,486.
However, in the majority of these techniques, the gas is extracted, the totality of the dissolved gas volume not being able to be collected and measured.
Although, in certain instances, an estimate of the quantity of dissolved gas can be carried out according to thermodynamic calculations (balance between the gas phase and the liquid phase), techniques for the partial extraction of dissolved gases do not make it possible to determine the exact composition of dissolved gases. Indeed light gases are extracted more easily, which leads to a heavy gas impoverishment of the extracted gas sample. Thus, the extracted gas is not representative of the quality of the gases dissolved in the fluid.
Other techniques, for example described in the patent documents U.S. Pat. No. 3,968,678, U.S. Pat. No. 4,681,601, and U.S. Pat. No. 4,394,635, were proposed to indirectly evaluate the volume of dissolved gases, without carrying out the extraction thereof.
However, these techniques do not make it possible at all to obtain exploitable information relating to the nature of the dissolved gases.